NPWT for Skin Grafts: Pressure Settings and Application Protocols
For skin grafts, use continuous negative pressure at -75 mmHg rather than the traditional -125 mmHg setting, maintain therapy for 4-7 days before first inspection, and recognize that lower pressures reduce inflammation while improving graft outcomes compared to standard wound NPWT protocols. 1, 2
Pressure Settings
Recommended Pressure Range
-75 mmHg is superior to -125 mmHg for split-thickness skin grafts based on molecular evidence showing reduced proinflammatory gene expression (S100A8 and Tenascin C downregulated 8-9 fold) and increased fibrinogen production at the lower pressure setting 1
The traditional -125 mmHg setting used for open wounds causes significantly more inflammation and less fibrinogen deposition in grafts within the first 3 hours of application 1
Lower pressure (-80 mmHg with gauze) produces thinner scar tissue (7 mm average depth) compared to higher pressure (-125 mmHg with foam, 18 mm average depth), resulting in more pliable reconstructed tissue 3
Continuous vs Intermittent
Continuous therapy is standard for skin grafts across all reported protocols 2, 1, 4
Intermittent therapy is not recommended for graft applications, as continuous pressure maintains consistent graft-to-bed contact during the critical imbibition and inosculation phases
Duration Before First Inspection
4-7 days is the typical duration before first dressing change and graft inspection 2, 4
Specifically, 4 days of NPWT post-graft application was successful in achieving complete healing in complex wounds 2
Average duration of 5.6-7.0 days post-graft is reported in contemporary practice, with the shorter duration (5.6 days) associated with single-use disposable systems 4
This extended period without inspection differs markedly from open wound NPWT, where dressing changes typically occur every 48-72 hours
Practical Differences from Open Wound NPWT
Pressure Modifications
Reduce pressure by approximately 40-50% compared to open wounds (from -125 mmHg standard to -75 to -80 mmHg for grafts) 2, 1, 3
The lower pressure prevents mechanical disruption of the delicate graft-bed interface during early healing phases 1
Dressing Change Frequency
Extended dressing intervals (4-7 days) versus 2-3 days for open wounds to avoid disturbing graft adherence 2, 4
No intermediate inspections should occur during the initial imbibition period (first 48-72 hours) when graft survival is most vulnerable
Interface Material Considerations
Low-adherence dressings are preferred over standard foam to minimize trauma during eventual removal 2
Gauze-based NPWT at -80 mmHg produces less sclerotic scar tissue and better tissue pliability compared to foam-based systems at -125 mmHg 3
Pain Management
Pain levels are generally moderate (4-5 on visual analog scale) and tend to decrease as therapy progresses, with lower pressures causing less discomfort than the -125 mmHg standard 2
The reduced pressure setting (-75 mmHg) improves patient comfort without compromising graft outcomes 1
Clinical Pathway Differences
NPWT over grafts facilitates immediate outpatient discharge (0.0 days average hospital stay) compared to 6.0 days with traditional rental NPWT systems, when using disposable single-patient-use devices 4
The sealed system protects the graft from external contamination and eliminates the need for traditional bolster dressings